Noctilucent CloudsOur connection with NASA's AIM spacecraft has been restored! New images from AIM show that the southern season for noctilucent clouds (NLCs) is underway. Come back to this spot every day to see AIM's "daily daisy," which reveals the dance of electric-blue NLCs around the Antarctic Circle..

THE SUN IS BLANK: For the 6th day in a row, the sun is blank--no sunspots. Almost half of the days in 2018 have been this way. Extended stretches of spotlessness are a herald of Solar Minimum. This "quiet" phase of the solar cycle brings extra cosmic rays, pink auroras, and a slight dimming of the sun. Cooling and contraction of Earth's upper atmosphere can also postpone the orbital decay of Chinese space stations. Stay tuned as the pendulum swings. Free:Aurora Alerts

EARTH'S MAGNETIC FIELD RINGING LIKE A BELL: Yesterday, a solar wind stream grazed Earth's magnetic field. Keyword: graze. The off-center impact of the solar wind caused something unusual to happen. Earth's polar magnetic field rang like a bell. Rob Stammes recorded the phenomenon from his magnetic observatory in Lofoton, Norway:

"On Feb. 22nd, the magnetic field around our observatory (as measured by ground currents) was swinging back an forth with a 100 second period," says Stammes. "This very stable oscillation went on for more than an hour."

This is quite different from what normally happens when a solar wind stream hits Earth, head-on. Here is an example of Stammes' recordings during a typical geomagnetic storm. Compared to the cacophany of a normal storm, yesterday's event was a sweet pure tone.

Researchers call these pure ultra-low frequency oscillations "pulsations continuous" (Pc). Pc waves energize particles in Earth's inner magnetosphere because they resonate with the natural motion of particles around the geomagnetic field. This energy, in turn, can supercharge the aurora borealis.

Indeed, hours after the Pc waves were observed, auroras exploded over Arctic Scandinavia. In Abisko, Sweden, Oliver Wright recorded three minutes of the display:

"I was guiding for Lights Over Lapland and we were treated to a fantastic geomagnetic storm," says Wright. "The auroras were so bright I just pointed my camera at the sky and recorded the lights in real time, hand-held."

The effect of the solar wind stream may be likened to a person blowing across the top of a soda bottle, the grazing breath producing a nearly monochromatic waveform. "This is quite rare," says Stammes. "Pulsating continuous signals like these are visible only 2 or 3 times a year."

RARE HAWAIIAN LIGHT PILLAR: Frankie Lucena of Puerto Rico frequently scans the automated Gemini webcam on Hawaii's Mauna Kea volcano, looking for sprites and other forms of exotic lightning. On Feb. 13th he saw something--but it wasn't lightning. "It was a rare Hawaiian light pillar," he says. Here is one frame from the complete video:

"I was searching for thunderstorms and just happened to come across this rarely seen event in this part of the world," says Lucena. "Light pillars usually occur in cold climates like Canada so to see them this far south is unusual."

Light pillars appear when urban lights reflect from the flat faces of ice crystals fluttering down from high freezing clouds. The source of the crystals, in this case, was probably a bank of altostratus/cumulus clouds shown in the video. "I do not recall seeing examples of these pillars so far south or in a location like Hawaii," says atmospheric optics expert Les Cowley. "So these are very rare indeed."

CROWD-FUNDING SPACE WEATHER RESEARCH: Did you know that cosmic rays in Earth's atmosphere are intensifying? It's true, and we are monitoring the phenomenon with regular space weather balloon flights to the stratosphere. This student science program is not supported by any government grant or corporate sponsorship. Instead, we raise our research funds by selling these:

On Dec. 31, 2017, the students of Earth to Sky Calculus flew a payload-full of these heart-shaped pendants to the stratosphere, 35.1 km (115,158 feet) above Earth's surface. They make great birthday and Mother's Day gifts.

You can have one for $119.95. Each glittering pendant comes with a greeting card showing the jewelry in flight and telling the story of its journey to the edge of space. Sales of this pendant support the Earth to Sky Calculus cosmic ray ballooning program and hands-on STEM research.

Every night, a network of NASA all-sky cameras scans the skies above the United States for meteoritic fireballs. Automated software maintained by NASA's Meteoroid Environment Office calculates their orbits, velocity, penetration depth in Earth's atmosphere and many other characteristics. Daily results are presented here on Spaceweather.com.

On Feb. 23, 2018, the network reported 16 fireballs.(16 sporadics)

In this diagram of the inner solar system, all of the fireball orbits intersect at a single point--Earth. The orbits are color-coded by velocity, from slow (red) to fast (blue). [Larger image] [movies]

Near Earth Asteroids

Potentially Hazardous Asteroids (PHAs) are space rocks larger than approximately 100m that can come closer to Earth than 0.05 AU. None of the known PHAs is on a collision course with our planet, although astronomers are finding new ones all the time.

Notes: LD means "Lunar Distance." 1 LD = 384,401 km, the distance between Earth and the Moon. 1 LD also equals 0.00256 AU. MAG is the visual magnitude of the asteroid on the date of closest approach.

Cosmic Rays in the Atmosphere

Readers, thank you for your patience while we continue to develop this new section of Spaceweather.com. We've been working to streamline our data reduction, allowing us to post results from balloon flights much more rapidly, and we have developed a new data product, shown here:

This plot displays radiation measurements not only in the stratosphere, but also at aviation altitudes. Dose rates are expessed as multiples of sea level. For instance, we see that boarding a plane that flies at 25,000 feet exposes passengers to dose rates ~10x higher than sea level. At 40,000 feet, the multiplier is closer to 50x. These measurements are made by our usual cosmic ray payload as it passes through aviation altitudes en route to the stratosphere over California.

What is this all about? Approximately once a week, Spaceweather.com and the students of Earth to Sky Calculus fly space weather balloons to the stratosphere over California. These balloons are equipped with radiation sensors that detect cosmic rays, a surprisingly "down to Earth" form of space weather. Cosmic rays can seed clouds, trigger lightning, and penetrate commercial airplanes. Furthermore, there are studies ( #1, #2, #3, #4) linking cosmic rays with cardiac arrhythmias and sudden cardiac death in the general population. Our latest measurements show that cosmic rays are intensifying, with an increase of more than 13% since 2015:

Why are cosmic rays intensifying? The main reason is the sun. Solar storm clouds such as coronal mass ejections (CMEs) sweep aside cosmic rays when they pass by Earth. During Solar Maximum, CMEs are abundant and cosmic rays are held at bay. Now, however, the solar cycle is swinging toward Solar Minimum, allowing cosmic rays to return. Another reason could be the weakening of Earth's magnetic field, which helps protect us from deep-space radiation.

The data points in the graph above correspond to the peak of the Reneger-Pfotzer maximum, which lies about 67,000 feet above central California. When cosmic rays crash into Earth's atmosphere, they produce a spray of secondary particles that is most intense at the entrance to the stratosphere. Physicists Eric Reneger and Georg Pfotzer discovered the maximum using balloons in the 1930s and it is what we are measuring today.